Turbine rotors



April 11, 1967 G. JENSON TURBINE ROTORS L5 Sheets-Sheet. 1

Filed June 8, 1966 FIGZ.

G. JENSON TURBINE ROTORS April 11, 1967 5 Sheets-Sheet 2 Filed June 8, 1966 G. J ENSQN TURBINE ROTORS April 11, 1967 5 Sheets-Sheet 3 Filed June 8, 1966 FIGED FIG.5C1

FIGBD FIGBQ United States Patent 3,313,519 TURBINE ROTGRS George Jenson, Manchester, England, assignor to Associated Electrical Industries Limited, London, England, a British company Filed June 8, 1966, Ser. No. 556,175 Claims priority, application Great Britain, June 22, 1965, 26,369/65 16 Claims. (Cl. 253-77) This invention relates to improvements in turbine rotors and relates more particularly to bladed discs therefor.

A large steam turbine includes two or more cylinders in each of which the turbine rotor is provided with several circumferential rows of blades, each row of blades comprising a stage of the turbine. The roots of the blades of each row are secured to the periphery of a disc which is itself secured to or is integral with the rotor shaft.

An object of the invention is to provide an improved bladed disc integral with or suitable for the rotor of a turbine.

According to one aspect of the present invention, in a bladed disc integral with or suitable for the rotor of a turbine and comprising a disc having a circumferential row of radially extending blades, the periphery of the disc and the radially inner ends of the blades being formed severally with at least one circumferential groove and with a co-operating circumferential tongue the crosssections of which permit the tongue to be inserted into the groove by a radial movement into a fitted position in which recesses formed in the sides of the groove are conjoined with recesses formed in the facing sides of the tongue to provide circumferentially extending channels into which are fitted members serving to lock the blades to the disc against radial movement, the members fitted into each channel constitute a hoop segmented to permit insertion of a segment of the hoop after a disc blade which it is to lock in place has been inserted radially into its fitted position, the circumferential extent of the blades being such that with all the blades in their fitted positions but at least some of the blades offset circumferentially from their final positions, the final segment of the hoop can be inserted in place, and locking means by which the blades, having been adjusted circumferentially to their final positions, can be retained in those positions against circumferential movement.

According to another aspect of the present invention, in a bladed disc integral with or suitable for the rotor of a turbine and comprising a disc having a circumferential row of radially extending blades, the periphery of the disc and the radially inner end of the blades being formed severally with at least one circumferential groove and with a co-operating circumferential tongue the cross-sections of which permit the tongue to be inserted into the groove by radial movement into a fitted position in which recesses formed in the sides of the groove are conjoined with recesses formed in the facing sides of the tongue to provide circumferentially extending channels into which fit members serving to look the blades to the disc against radial movement, the members fitted into each channel constitute a segmented hoop one portion of which, having a length at least equal to the circumferential width of a blade root, can be left out during assembly to permit radial insertion of the blades, the circumferential extent of the blade roots being such that with all the blades in their correct radial positions but at least some of the blades ofiset circumferentially from 'their final positions, a gap is left at least equal to the circumferential width of a blade root, the one final portion of the hoop being inserted into that gap, and locking means by which the blades, having been adjusted cirldl jl Patented Apr. 11, 1957 cumferentially to their final positions, can be retained in those positions against circumferential movement.

Preferably the locking means are spacing members inserted between adjacent blades, arranged preferably so as to lock also the hoop segments against moving in the peripheral direction.

According to another aspect of the present invention in a method of manufacture of a bladed disc integral with or suitable for the rotor of a turbine and comprising a disc having a circumferential row of radially extending blades, the periphery of the disc and the radially inner ends of the blades being formed severally with at least one circumferential groove and with a co-operating circumferential tongue, the cross-sections of which permit the tongue to be inserted into the groove by radial movement into a fitted position in which recesses formed in the sides of the grooves are conjoined with recesses formed in the facing sides of the tongue to provide circumferentially extending channels into which are fitted members serving to lock the blades to the disc against radial movement, the whole of the blades, or the whole of a group of blades, except that the last blade in the group, are inserted radially into their fitted positions, the members fitted into the channel in the form of segments of a hoop, are inserted into the channels to lock these blades in their fitted positions, the blades being offset circumferentially from their final positions to permit the final blade to be fitted radially and then moved circumferentially to permit the final segment of the hoop to be inserted in place, the blades then being adjusted circumferentially to their final positions, and locking means then being applied by which the blades are retained in those positions against circumferential movement.

According to yet another aspect of the present invention in a method of manufacture of a bladed disc integral with or suitable for the rotor or a turbine and comprising a disc having a circumferential row of radially extending blades the periphery of the disc and the radially inner ends of the blades being formed severally with at least one circumferential groove and with co-operating circumferential tongue, the cross-sections of which permit the tongue to be inserted into the groove by a radial movement into a fitted position in which recesses formed in the sides of the grooves are conjoined with recesses formed in the facing sides of the tongue to provide circumferenti'ally extending channels into which fit members serving to lock the blades to the disc against radial movement, the members in the form of segments of a hoop are inserted into the recesses in the disc leaving a gap having a length at least equal to the circumferential width of a blade root, the blades are then inserted radially into this gap and slid around the circumference of the disc until all the blades are assembled on the disc but at least some of the blades are offset circumferentially from the final positions to permit the final segment of the hoop to be inserted in place, the blades then being adjusted circumferentially to their final positions, and locking means then being applied by which the blades are retained in those positions against circumferential movements.

The invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a view of one bladed disc of a rotor of a steam turbine taken in an axial direction at a stage in the assembly when all the blades have been assembled on the disc.

FIGURE 2 is a section taken on the line II-lI in FIGURE 3 and showing four of the rotor blades;

FIGURE 3 is a section taken on the, line III-J11 in FIGURE 1;

FIGURE 4 is a view of three of the rotor blades shown in FIGURE 1 but at a stage in the assembly subsequent to r 3 that depicted in FIGURE 1, and drawn to a larger scale than in that figure;

FIGURES a and 5b are respectively a side elevation and an end elevation of a locking plate shown in FIG- URE 4;

FIGURES 6a and 6b are respectively a side elevation and end view of a spacing member shown in FIGURE 4; and

FIGURE 7 is a fragmentary view of an alternative embodiment of the invention showing a different crosssectional shape for the locking rings.

Referring first to FIGURES 1 to 6, a turbine rotor shaft 1 has secured to it a number of bladed discs of which one disc 2 is shown. The disc 2 is machined at its periphery to provide three substantially V-shaped circumferential grooves 3A, 3B and 3C into which fit respective V-shaped tongues 4A, 4B and 4C machined on the roots of the blades 5. The facing sides of the tongues 4 and grooves 3 are provided with pairs of facing, substantially semicircular, recesses 6A and 6B, which are conjoined to form apertures 6 which in cross-section consist of a number of substantially circular portions connected together by narrow neck-like portions and which extends around the whole circumference of the disc 2 and blade roots. These apertures 6 are arranged to receive locking rings 7 comprising a number of substantially cylindrical ribs connected together by web-like portions and which are formed by two or more segments 7A, 7B of suitable length to enable the bladed disc to be assembled by the method which is described below. The roots of the blades 5 have pitch lengths 8 which are less than the circumference of the disc divided by the number of blades, by an amount sufiicient to leave, when all the blades are assembled on the disc 2 as shown in FIGURE 1, a gate 9 of length somewhat greater than one blade pitch. The periphery of the disc is provided with two axially extending slots 10 and 11 spaced one blade pitch length apart and each arranged to receive a locking plate 12 shaped as shown in FIGURE 5. The roots of the blades are also provided in their abutting surfaces (see FIGURE 2) with substantially rectangular recesses 14 into which can be fitted blade spacing members 15 shown in FIGURE 6.

To assemble the bladed disc, a blade 5 is arranged on the periphery of the disc 2 with the tongues 4 engaging the grooves 3 and segments 7A of the locking rings are inserted in the apertures 6 to lock that blade to the periphery of the disc. Further blades 5 and segments 7A are then added until all the blades 5 are assembled on the periphery of the disc as shown in FIGURE 1 leaving the gate 9 at the position on the periphery of the disc containing the slots 10 and 11. The segments 7A are arranged to be of dimensions such that they terminate substantially flush with the circumferentially outermost sides of the two slots 10 and 11. Segments 7B are then inserted in recesses 6B these segments having a length such that their ends lie substantially flush with the circumferentially innermost sides of the two slots 10 and 11. A blade from one side of the gate 9 is then slid circumferentially along the tongues 4 and segments 7B so that the segments 7B lie within recesses 6A in that blade root. Locking plates 12 are then inserted in the slots 10 and 11 each locking plate 12 lying between adjacent ends of the segments 7A and 7B and restraining the blade 5 and the segments 7A and 7B from circumferential movement. The remainder of the blades 5 are slid circumferentially along the tongues 4 and segments 7A so that the blades are evenly distributed around the periphery of the disc, spacing members 15 being inserted in the recesses 14 be tween each two adjacent blades 5. The insertion of the last spacing member 15 securely locks all the blades to the disc, radial movement of the blades being prevented by the locking rings 7 and circumferential movement of the blades 5 and the locking rings 7 being prevented by the locking plates 12 and spacing members 15.

In an alternative method of assembling the bladed disc, the segments 7A are inserted in the recesses 63 leaving a gap at the position on the periphery of the disc containing the slots 10 and 11. A blade 5 is then inserted radially into this gap so that the tongues 4 engage the grooves 3, and the blade is slid circumferentially along the tongues 4 and segments 7A. The remainder of the blades 5 are then inserted in the same manner leaving the gate 9 at the position on the periphery of the discs containing the slots 10 and 11. The segments 7B are then inserted in recesses 63 and a blade 5 from one side of the gate 9 is then slid circumferentially along the tongues 4 and segments 7B so that the segments 7B lie Within recesses 6A in that blade root. Locking plates 12 are then inserted in the slots 10 and 11 and the remainder of the blades are adjusted circumferentially and spacing members 15 inserted in the recesses 14. The insertion of the last spacing member 15 securely locks all the blades to the disc, radial movement of the blades being prevented by the locking rings 7 and circumferential movement of the blades being prevented by locking plates 12 and spacing members 15.

In an alternative arrangement the recesses in the sides of the tongues 4 and the sides of the grooves 3 are substantially V-shaped and are conjoined to receive locking rings 7 having a Zig-zag or stepped cross-sectional shape as shown in FIGURE 7.

A bladed disc in accordance with the invention is advantageous in that all the blades and all positions on the periphery of the disc are uniformly stressed, there being no closing blade which usually is of different design to the remainder. Moreover theperiphery of the disc has no parasitic idle mass as in other blade fastenings having pin or serrated roots.

What I claim is:

1. A bladed disc of a rotor of a turbine comprising:

(a) a disc;

(b) a circumferential row of blades extending radially from the disc;

(c) at least one circumferential tongue and a co-operating circumferential groove provided on the periphery of the disc and the radially inner ends of the blades, the tongue and the groove having crosssections which permit the tongue to be inserted in the groove by a radial movement into a fitted position;

(d) recesses formed in the sides of the groove and in the facing sides of the tongues which are conjoined to provide circumferentially extending channels for receiving members serving to lock the blades to the disc against radial movement;

(e) locking members fitted into each channel constituting a hoop segment to permit insertion of a segment of the hoop after a blade which it is to lock has been inserted radially into its fitted position, the circumferential extent of the blades being such that with all the blades in their fitted positions but at least some of the blades ofiset circumferentially from their final positions, the final segment of the hoop can be inserted in place; and

(f) locking means by which the blades, having been adjusted circumferentially to their final positions, can be retained in those positions against circumferential movement, said recesses being substantially semi-circular and conjoined to form said circumferentially extending channels, which channels, in cross-section, consist of substantially circular portions connected together by narrow neck-like portions and which receive the hoop segments which comprise substantially cylindrical ribs connected together by Web-like portions.

2. A bladed disc as claimed in claim 1, wherein the locking means are spacing members inserted between adjacent blades.

3- .A bladed disc as claimed in claim 1, wherein the locking means are arranged to lock the hoop segments against moving in the peripheral direction.

4. A bladed disc as claimed in claim 1, wherein the circumferential tongue and co-operating circumferential groove are substantially V-shaped.

5. A bladed disc of a rotor of a turbine comprising:

(a) a disc;

(b) a circumferential row of blades extending radially from the disc;

(c) at least one circumferential tongue and a co-operating circumferential groove provided on the periphery of the disc and the radially inner ends of the blades, the tongue and the groove having cross-sections which permit the tongue to be inserted into the groove by a radial movement into a fitted position;

(d) recesses formed in the sides of the groove and in the facing sides of the tongue which are conjoined to provide circumferentially extending channels for receiving members serving to lock the blades to the disc against radial movement;

(e) locking members fitted into each channel constituting a segmented hoop, one portion of which, having a length at least equal to the circumferential width of a blade root, can be left out during assembly to permit radial insertion of the blades, the circumferential extent of the blade roots being such that with all the blades in their correct radial positions but at least some of the blades olfset circumferentially from their final positions, a gap is left at least equal to the circumferential width of one blade root, the one final portion of the hoop being inserted into that gap; and

(f) locking means by which the blades, having been adjusted to their final positions, can be retained in those positions, against circumferential movement, said recesses being substantially semi-circular and conjoined to form said circumferentially extending channels, which channels, in cross-section, consist of substantially circular portions connected together by narrow neck-like portions and which receive the hoop segments which comprise substantially cylindrical ribs connected together by web-like portions.

6. A bladed disc as claimed in claim 5, wherein the locking means are spacing members inserted between adjacent blades.

7. A bladed disc as claimed in claim 5, wherein the locking means are arranged to lock the hoop segments against moving in the peripheral direction.

8. A bladed disc as claimed in claim 5, wherein the circumferential tongue and co-operating circumferential groove are substantialy V-shaped.

9. A bladed disc of a rotor of a turbine comprising:

(a) a disc;

(b) a circumferential row of blades extending radially from the disc;

(c) at least one circumferential tongue and a co-operating circumferential groove provided on the periphery of the disc and the radially inner ends of the blades, the tongue and the groove having cross-sections which permit the tongue to be inserted in the groove by a radial movement into a fitted position;

(d) recesses formed in the sides of the groove and in the facing sides of the tongue which are conjoined to provide circumferentially extending channels for receiving members serving to lock the blades to the disc against radial movement;

(e) locking members fitted into each channel constituting a hoop segment to permit insertion of a segment of the hoop after a blade which it is to lock has been inserted radially into its fitted position, the circumferential extent of the blades being such that with all the blades in their fitted positions but at least some of the blades offset circumferentially from their final positions, the final segment of the hoop can be inserted in place; and

(f) locking means by which the blades, having been adjusted circumferentially to their final positions, can be retained in those positions against circumferential movement,

said recesses being substantially V-shaped and conjoined to form said circumferentially extending channels, which channels are of zig-zag cross-sectional shape and receive the said hoop segments which are of corresponding zig-zag cross section.

10. A bladed disc as claimed in claim 9, wherein the locking means are spacing members inserted between adjacent blades.

11. A bladed disc as claimed in claim 9, wherein the locking means are arranged to lock the hoop segments against moving in the peripheral direction.

12. A bladed disc as claimed in clam 9, wherein the circumferential tongue and co-operating circumferential groove are substantially V-shaped.

13. A bladed disc of a rotor of a turbine comprising:

(a) adisc;

(b) a circumferential row of blades extending radially from the disc;

(c) at least one circumferential tongue and a co-operating circumferential groove provided on the periphery of the disc and the radially inner ends of the blades, the tongue and the groove having cross-sections which permit the tongue to be inserted into the groove by a radial movement into a fitted position;

(d) recesses formed in the sides of the groove and in the facing sides of the tongue which are conjoined to provide circumferentially extending channels for receiving members serving to lock the blades to the disc against radial movement;

(e) locking members fitted into each channel constituting a segmented hoop one portion of which, having a length at least equal to the circumferential width of a blade root, can be left out during assembly to permit radial insertion of the blades, the circumferential extent of the blade roots being such that with all the blades in their correct radial positions but at least some of the blades offset circumferentially from their final positions, a gap is left at least equal to the circumferential width of one blade root, the one final portion of the hoop being inserted into that gap; and

(f) locking means by which the blades, having been adjusted to their final positions, can be retained in those positions, against circumeferential movement,

said recesses being substantially V-shaped and conjoined to form said circumferentially extending channels, which channels are of Zig-zag cross-sectional shape and receive the said hoop segments, which are of corresponding zig-zag cross section.

14. A bladed disc as claimed in claim 13, wherein the locking means are spacing members inserted between adjacent blades.

15. A bladed disc as claimed in claim 13, wherein the locking means are arranged to lock the hoop segments against moving in the perihperal direction.

16. A bladed disc as claimed in claim 13 wherein the circumferential tongue and co-operating circumferential groove are substantially V-shaped.

No references cited.

MARTIN P. SCHWADRON, Primary Examiner.

E. A. POWELL, 1a., Assistant Examiner. 

1. A BLADED DISC OF A ROTOR OF A TURBINE COMPRISING: (A) A DISC; (B) A CIRCUMFERENTIAL ROW OF BLADES EXTENDING RADIALLY FROM THE DISC; (C) AT LEAST ONE CIRCUMFERENTIAL TONGUE AND A CO-OPERATING CIRCUMFERENTIAL GROOVE PROVIDED ON THE PERIPHERY OF THE DISC AND THE RADIALLY INNER ENDS OF THE BLADES, THE TONGUE AND THE GROOVE HAVING CROSSSECTIONS WHICH PERMIT THE TONGUE TO BE INSERTED IN THE GROOVE BY A RADIAL MOVEMENT INTO A FITTED POSITION; (D) RECESSES FORMED IN THE SIDES OF THE GROOVE AND IN THE FACING SIDES OF THE TONGUES WHICH ARE CONJOINED TO PROVIDE CIRCUMFERENTIALLY EXTENDING CHANNELS FOR RECEIVING MEMBERS SERVING TO LOCK THE BLADES TO THE DISC AGAINST RADIAL MOVEMENT; 